Azilsartan Impurity S Catalogue A195639 CAS 139481-44-0 M.W 411.46 M.F C25H21N3O3 Specifications FAQs methyl 1-((2'-cyano-[1,1'-biphenyl]-4-yl)methyl)-2-ethoxy-1H-benzo[d]imidazole-7-carboxylate